This invention relates to a chain driving mechanism for a bicycle or the like comprising a wheel-side sprocket unit, a pedal crank-side sprocket unit and a chain drivingly connecting said sprocket units.
Modern gear change mechanisms of bicycles and the like have a large number of sprockets located at the driven wheel and connected with a free wheel mechanism. An increasing number of sprocket wheels is also provided on the shaft of a pedal crank. By this large number of sprockets and sprocket wheels one can fulfill the requirements to different special bicycles and more particularly with racing bicycles and mountain bicycles. By such a large number of sprockets and sprocket wheels one can obtain a great difference of the extreme transmission ratios. Moreover, one can also fulfill the requirement to obtain very small changes of transmission ratios between mutually adjacent transmission ratios.
By providing a plurality of sprockets not only at the rear wheel but providing in addition a number of sprocket wheels on the shaft of the pedal crank, one could obtain acceptable axial widths of the sprocket units and, nevertheless, obtain a factor 4 between the extreme transmission ratios.